When a narrowed or obstructed part is formed in a blood vessel, bile duct, pancreatic duct and the like, the flow of blood, bile (gall), pancreatic fluid and the like may be hindered. Conventionally, a treatment for improving the flow of blood, bile (gall), pancreatic fluid and the like is widely performed by inserting a guide wire into a narrowed or obstructed part, and then expanding the narrowed or obstructed part with a balloon catheter which follows the guide wire.
Various guide wires intended for guiding a balloon catheter to a narrowed or obstructed part have been proposed. For example, Japanese Patent No. 4354523 discloses a guide wire comprising a core shaft, a coil body covering a distal end portion of the core shaft and formed with one wound element wire and a distal end fixed portion where the distal end of the core shaft is fixed to the distal end of the coil body. Japanese Patent Application Laid-Open No. 2008-155052 discloses a guide wire comprising a core shaft, a coil body covering a distal end portion of the core shaft and formed with spirally wound multiple element wires and a distal end fixed portion where the distal end of the core shaft is fixed to the distal end of the coil body.
However, in such guide wires, multiple element wires of a coil body are not welded to each other at the distal end of the coil body. Therefore, when fixing the distal end of a core shaft to the distal end of a coil body at a distal end fixed portion, the following problems occur: (i) the distal end fixed portion may flow towards the proximal end side along the surfaces of all of the multiple element wires, and thus the length of the distal end fixed portion is difficult to control; and (ii) the multiple element wires of the coil body may become unwound, and thus the distal end fixed portion is difficult to be fixed to the distal end of the coil body.
Further, although it is not a guide wire, a catheter is known in which an end of a coil body formed with spirally wound multiple element wires is connected to an end of a braid by welding. In that known catheter, the braid comprises a first element wire and a second element wire braided in a net-like structure (see Japanese Patent Application Laid-Open No. 2012-192177). In the catheter described in Japanese Patent Application Laid-Open No. 2012-192177, multiple element wires of the coil body are melted together to fix the element wires to each other in order to improve the connectivity between the coil body and the braid.
When the coil body disclosed in Japanese Patent Application Laid-Open No. 2012-192177 is applied to the guide wires of the Japanese patent and published application described above, the flow of the distal end fixed portion towards the proximal end side along the multiple element wires might be prevented, and further the distal end fixed portion might be easily fixed to the distal end of the coil body. However, the tensile strength of the distal end fixed portion becomes weak, resulting in a risk that the distal end fixed portion becomes detached from the distal end of the coil body since the distal end fixed portion is only fixed to an end face of the distal end of the coil body (in other words, the distal end fixed portion does not flow towards the proximal end side along the multiple element wires at all).